The present invention relates to an indicator of the said type warns the user when the clutch has become worn to such an extent that there is a risk that the servo piston will come into contact with the rear end wall of the servo housing, thus avoiding that the clutch is not completely engaged. An indicator of this type is known, e.g., from U.S. Pat. No. 4,084,671. The indicator described therein provides a connection between the cylinder space and the atmosphere when it is actuated. The pressure in the cylinder space is Thereby lowered, the servo effect thus being reduced and the clutch pedal becoming correspondingly heavy to operate. This indicator, however, causes a major leakage of air, which is undesirable, since such a leakage also affects other user systems.
Furthermore it is known that a separate choke valve can be provided the air supply line to the servo unit, but the installation of such choke valve is expensive.
The object of the device according to the invention is to provide an indicator device of the known type, which is not encumbered by the above-mentioned disadvantages.
The characteristics of the device according to the invention are characterized by the features in the claims presented.